Professor of Biology
Current Research
Research in the Mullen lab is aimed at understanding the origin and maintenance of diversity at all levels of biological organization. Within this broader context, we are particularly interested in the link between divergent natural and sexual selection of adaptive traits (e.g. – mimicry in butterflies) and the origins of barriers to gene exchange between closely-related populations (i.e. – speciation).
Current projects in the lab have focused on addressing fundamental questions about patterns of biodiversity (e.g. – latitudinal gradients in species richness), and the role that life history evolution plays in driving adaptive diversification at both the larval and adult life-history stage among Neotropical Adelpha butterflies.
Students and postdocs in the lab employ a wide-variety of approaches, including: RAD-based phylogenetics and QTL-mapping, comparative and population genomic analyses of whole genome sequence data, RNA-seq, functional assays (e.g. -CRISPR/Cas9), as well as more traditional ecological techniques (e.g. – model-based predation experiments, behavioral and chemical assays of hostplant preference and performance).
Selected Publications
- Robinson, A.E., et al., including Mullen, S.P. 2025. Is temporal synchrony necessary for effective Batesian mimicry? Proceedings of the Royal Society B 292:20241737.
- Novick, I., et al., including Mullen, S.P. 2025. Ultraconserved elements reveal the relationship between facultative keratinophagy and synanthropic evolution in clothes moths. Molecular Ecology 34:e17799.
- Robinson, A.E., Herrmann, J., Aichelman, H.E., & Mullen, S.P. 2025. Citizen science supports ecological predictions of phenology in North American mimetic butterflies. Biological Journal of the Linnean Society 146:blaf068.
- Chazot, N., et al., including Mullen, S.P. 2021. Conserved ancestral tropical niche but different continental histories explain the latitudinal diversity gradient in brush-footed butterflies. Nature Communications 12:5717.
- Mullen, S.P., et al. 2020. Disentangling population history and character evolution among hybridizing lineages. Molecular Biology and Evolution 37:1295-1305.
- Semenov, G.A., et al., including Mullen, S.P. 2019. Unifying theoretical and empirical perspectives on genomic differentiation. Trends in Ecology & Evolution 34:987-995.
- Finkbeiner, S.D., et al., including Mullen, S.P. 2018. Frequency-dependence shapes the adaptive landscape of imperfect Batesian mimicry. Proceedings of the Royal Society B 285:20172786.
- Kunte, K., et al., including Mullen, S.P. 2014. doublesex is a mimicry supergene. Nature 507:229-232.